Doxorubicin is a chemotherapy drug used to treat a wide range of cancers by preventing cancer cells from replicating. Red in color, it can cause unfortunate side effects to the patient, thus its nickname the "red devil."

This image, captured with an epifluorescence microscope, shows neural pathways known as "fiber tracts" that are trapped on hexagonal microstructures made of silicon. The fiber tracts light up in a violent red as soon as they absorb the doxorubicin molecules.